Calculate age of items and divide them in age groups

Hello dear members!

I am facing the following problem:

I have a set of data in this form for some equipment

year_of_build -----end_of_product_life
----1980----------------1995
----1981----------------2012
----1981----------------
----1982----------------2011
etc


the data are about 10000 entries and where there is no date in the end_of_product_life column it means it is still functioning
I want to calculate for the years 1990 through 2012 how many items were still in service and divide them in age subcategories like

--------0-5 6-10 11-15 16-20 over_20
1990
1991
1992
etc

is there any elegant way to do it?

what I have done is to calculate in a differrent sheet the age of each item from the relevant year and then do a countif() in a seperate column or sheet

the function I used is IF(AND(all!$F2<A$1,all!$O2>A$1),A$1-all!$F2," ") which says if the year_of_build is lesser than the year_of_calculation (build 1980, year of calculation 1990) AND year_of_end_of_life is greater than the year_of_calculation (end of life 1995, year of calculation 1990) then give me the age in the form of year_of_calculation - year_of_build (1990-1980) else return empty cell


Then I can go make another calcualtion and divide them in subcategories with some CountIFS() functions which I also know how to make

The question again is:

Can I do this directly in a form of

--------0-5 6-10 11-15 16-20 over_20
1990
1991
1992
etc


Thank you for the time reading this and thank you even more for the time you might spend to solve and answer

Happy Holidays to everybody
Markos